 Alexander von Humboldt's (1769–1859) work as a natural scientist and explorer was foundational to biogeography.Wladimir Köppen (1846–1940) was an eclectic Russian-born botanist and climatologist who synthesized global relationships between climate, vegetation and soil types into a classification system that is used, with some modifications, to this day.Alfred Wegener (1880–1930), a similarly interdisciplinary scientist, was one of the first people to hypothesize the theory of continental drift which was later developed into the overarching geological theory of plate tectonics.